<script>
        var user = prompt("Who's there?");
        if (user == "Admin") {
            var password = prompt("Password?");
            if (password == "TheMaster") {
                alert("Wellcome!");
            } else if (password == null) {
                alert("Canceled!");
            } else {
                alert("Wrong password!");
            }
        } else if (user == null) {
            alert("canceled!");
        } else {
            alert("I don't know you!");
        }
    </script>

اینجا اگه کاربر cancel رو وارد کنه alert("canceled!") اجرا میشه’’